Early implementation of shock absorbers on recreational type snow vehicles, commonly referred to as snowmobiles, involved the mounting of the shock absorbers alongside the conventional leaf springs on the upper sides of the vehicle skis; however, such use of the shock absorbers was found to be objectionable due to the fact that the geometry did not permit use of the entire stroke of the shock absorber during operation thereof. As an alternative, it has heretofore been proposed to eliminate the use of the leaf spring and utilize a trailing arm on each ski of the vehicle which was pivoted about the front end of the ski and provided with a shock absorber between the rear end of the trailing arm and the rear of the ski. Such a snowmobile suspension provided a superior ride by utilizing a lower rate conical spring beneath the trailing arm to work in conjunction with the shock absorber. This arrangement, however, was subject to some criticism due to the fact that the arrangement was quite expensive to fabricate and gave the front end of the vehicle a "cluttered" look. Accordingly, most snowmobile manufacturers that utilize shock absorbers place them over or beside the leaf spring in the manner originally proposed. This arrangement involves the orientation of the shock absorbers at approximately 15.degree. from the horizontal. As previously mentioned, however, this arrangement permits only approximately 1-3/4 inch of useful travel of the shock absorber piston, as compared to almost 3-1/2 inches of travel that the associated leaf springs undergo.
The present invention provides a new and improved snowmobile suspension strut which obviates the objectionable features of each of the aforementioned types of snowmobile suspensions heretofore used. More particularly, the snowmobile suspension of the present invention utilizes a pair of suspension struts that are associated one with each side of the vehicle skis and which entirely eliminate the need for conventional leaf springs, as well as the need for trailing arms as incorporated in a snowmobile suspension of the type shown in U.S. Ser. No. 71,088, filed Sept. 10, 1970, owned by the common assignee of the subject invention. Generally speaking, the suspension struts for the present invention are used to replace the original ski spindles on the snowmobile vehicle, and the struts include a pair of generally tubular shaped cylindrical housings that are fixedly secured to the underside of the snowmobile and within which the shock absorber housings are telescopically received. The lower ends of the shock absorber housings are secured to the associated skis and the piston rods of the shock absorbers located within the shock absorber housings are fixedly secured to the frame or other suitable portion of the vehicle. The suspension springs are in the form of helical coil springs and are arranged coaxially of the piston rods between the upper ends of the struts and the aforesaid portions of the vehicle to which the piston rods are affixed. The original steering mechanism of the vehicle is secured via a pair of steering arms which are non-rotatably secured to the shock absorber housings and permit longitudinal sliding movement of the shock absorber housings, whereby to provide steering capability of the skis in response to operation of the steering mechanism of the snowmobile. As will hereinafter be described in detail, the strut design eliminates the conventional leaf spring and spindle construction and the struts are oriented in a plane at approximately 30.degree. from vertical, whereby when the vehicle skis ride over a bump or other severe terrain variation, the struts will not only move upwardly, but rearwardly. One particular feature of the present invention resides in the fact that the elimination of the leaf springs permits greater freedom of design, although the real "forte" of the present invention resides in the increased stability of the front end of the snow vehicle due to the fact that the skis are maintained in engagement with the terrain with a somewhat greater degree than with prior known snowmobile suspensions. This, of course, assures improved steering ability and reduced rider fatigue, as well as increased rider safety.